The present invention relates to an RF spectrum measurement analyzer and method and more particularly to a GSM output RF spectrum measurement analyzer and corresponding method.
GSM, or Global System for Mobile Communications, is a worldwide standard for digital mobile telephones. Traditionally, in output RF spectrum analysis techniques, a swept tuned analyzer is used in zero span mode to make measurements, relying on a hardware implemented resolution bandwidth filter (RBW) which may or may not be what is specified in the GSM Standard. The prior art techniques do not provide for any flexibility for a user to use a different filter type. Also, the measurement had to be performed by tuning the analyzer L.O. (Local Oscillator) individually to each offset frequency of the test.
In view of the foregoing, it would be desirable to provide an improved GSM output RF spectrum measurement analyzer and corresponding method.
It is an object of the present invention to provide an RF spectrum measurement analyzer and method and more particularly to a GSM output RF spectrum measurement analyzer and corresponding method. One preferred embodiment of the present invention is applicable to GSM applications. However, other embodiments could be applicable to the general class of Time Division Multiple Access (TDMA) signals of which GSM, PDC (Pacific Digital Cellular), NASC and the like are a part.
According to one preferred embodiment of the present invention, the method includes the steps of An RF spectrum measurement analyzer method comprising the steps of: acquiring an RF carrier signal; converting the acquired RF carrier signal to an IF signal; converting the IF signal to a digital signal of relatively wide bandwidth; FFT filtering the digital signal to measure multiple offset frequencies within the IF bandwidth; and mathematically applying a resolution bandwidth filter at each offset. A further embodiment includes the steps of inverse FFT filtering the output of the resolution bandwidth filter and measuring the power in the time domain.